A shipwreck is often the only thing standing up from a flat seabed plain. Consequently, it becomes a magnet for all kinds of fish, shellfish and other marine life. Big conger eels live in most shipwrecks. Lobsters call them home. So do big crabs. And huge shoals of pouting and pollack are always to be found circling around.However, there are serious dangers that must be watched. There is little danger from sealife as big congers will not attack you, nor will big lobster or crab unless you put your hand in their claws.
The real dangers are the depth and the time spent underwater which must never be forgotten. Decompression sickness – the “bends” – is always waiting to strike divers who break the rules and make fast ascents from deep wrecks. The British Sub-Aqua Club has always recommended 50 metres as the sensible limit for experienced amateurs diving using compressed air. Wreck divers should stick to that limit, even though modern gas mixtures appear more tolerant than compressed air. They should be wary too of their depth when exploring the ship. The inside may be much deeper than the outside if the ship has sunk into a soft seabed.
Wreck diving is not for the inexperienced and has it’s own special dangers. Like all amateur diving, it is never carried out alone. There is the risk of running low on air due to becoming absorbed in exploring the wreck, or getting entangled in a fishing net (sometimes many nets are draped over one ship). The wreck diver is bound to consider exploring inside the wreck if a suitable hole or entrance is found. However wreck penetration is the most dangerous part of this kind of diving.
Even swimming under a piece of wreckage is dangerous. Hanging wreckage may be so unstable that it will fall because of the disturbance which is caused by the diver’s exhaust bubbles or fin movements. One diver on a wreck recently was trapped by a steel door falling on him and pinning him to the seabed. He was saved by the prompt action of his buddy diver.
A number of divers have died trapped in wrecks. Silting of a wreck takes place very quickly after her sinking. This makes it very dangerous to enter a wreck without some foolproof method of return to a clear exit point. One such method is a lifeline. A few fin strokes inside a wreck are enough to turn visibility into absolute zero. In that black cloud, even the powerful torches which every wreck diver carries, could not show them a way out to the open sea. Wreck penetration is not a spur of the moment thing. It has to be carefully planned in the same way as cave diving.
There are certain wrecks that are protected by law. These are wrecks of historic importance and “War Graves”. Forty-eight wrecks dating from a Bronze Age galley to a submarine of 1880 are designated under the Protection of Wrecks Act of 1973 and all diving on them is banned without special permission. A classic example of this kind of wreck is Henry VIII’s flagship Mary Rose, sunk in 1545. After being found by amateur divers, she was protected until raised and put on show at Portsmouth. It is also possible to see some protected wrecks through the Nautical Archaeology Society.
The Military Remains Act of 1986 puts other restrictions on some wrecks of ships and aircraft “known to contain remains of service personnel”. Though divers may visit these “war graves”, it is only on a look-but-no-touch basis. Divers may not enter such wrecks, disturb them or remove any artifacts.
Wreck divers like to collect souvenirs from wrecks but every item recovered from a wreck must be reported to the Receiver of Wreck at the Coastguard Agency in Southampton. In the case of a small fairly modern item, such as a porthole, the diver is usually allowed to keep it. Other more valuable items are held by the Receiver for a year and a day and, if not claimed by their owner during that time, become the property of the Crown. They then may be auctioned. In such a case the diver is entitled to a salvage award from the proceeds.